Oil spray nozzles

[JeepSJ]

In the reworking of my DieselSJ project, I'm looking at rebuilding the engine. There was some cylinder scoring when I installed it and it has always burned some oil and had more blow-by than I was comfortable with. So I am going to do an 18:1 build.

The question lies with the oil squirters. The block is a 1997 (506 I think - I need to verify tonight). When it was hot, idle oil pressure was 15-17. It came right up as RPM increased, but I always thought that was too low. I did measure the oil clearances when I installed the engine and they were all within spec.

I know with later blocks, the squirt nozzles were reduced in size. A search has come up empty, but I was wondering if the later nozzles could be installed so that I'm not bleeding as much oil through the squirters, which I hope would help with my low oil pressure.

Thoughts?

[Robyn]

Hi

The early squirter blocks had a larger body size on the nozzles, but the oil holes are the same size.

This was done to reduce the "weakening" in the main saddle from the HUGE hole that was used for the early nozzles.

ALWAYS DEBUR the oil holes to get rid of the stress riser.

Just breaking the edge of the hole with a counter sink is all that's needed.

maybe 1/64th inch wide chamfer, NO MORE

Yesssss, these engines idle oil pressure really suck.

I built a fresh 6.5 on an AMG bare block I scared up (long story, and they are not normally available)

It has the small squirt nozzles in all the main saddles.

Hot Idle pressure is about what you posted.

The running pressure will still make one nervous.

A little trick.

When you purchase your main bearings, get an early set that does not have the oil holes in the upper half of the shell.

Get a separate set that has the squirt holes and then mix and match.

Use the ones with the squirt holes for the rear main (squirters on 7 and 8) and use the shells without the squirt holes on the others.

The other option is to get some aluminum rod and make 6 little plugs the same diameter as the factory squirters that are there and tap them into to squirter bores on 1 - 6

The only reason for these squirters is to help cool the piston crowns and especially on 7-8 as they run hotter and are clearance'd more anyway at (.0005 more than the others)

With an 18:1 engine you are fine.

Use the back 2 squirters only

The idle oil pressure will go up to about 40 and running pressure at about 60

The early engines did not have the squirts and did fine.

This was an attempt to fix an issue that really was not an issue.

I have seen early 6.5's with 200k miles plus that looked great inside.

Keeping the EGT and boost where it should be is far more important than those OIL LEAKS

I always run a can of STP with the 15-40 oil in the squirt engines.

That 15 psi idle pressure just gives me the willies.

Not a big deal on a little 350 mouse motor, but I like oil pressure on these engines.

Always use the bigger oil pump even with only 2 squirts.
These leaks lose a lot of oil.


Good luck

[JohnC]

Counterpoint: There's nothing wrong with 15 psi at idle. As long as you have more PSI than rpm (40+ psi for 4000 RPM, for example) the engine will be fine.

YMMV...

[Robyn]

Still makes me nervous seeing that gauge bumping the low peg.

Granted, the electric dash gauges are barely above a guessing stick, but seeing 30-35 psi at idle and 60 at running speed makes me feel far more "warm and fuzzy"

My experience was with a fresh engine, new crank, new bearings and everything all nice and tidy.

After some miles the clearance is going to open up and the oil "leaks" are only going to get bigger.

Even plugging the two front squirters will help a bunch.

If I could do over the engine I built for the Dahooooley, knowing what I know now I would have used the older style bearings and not used the squirters at all.

The one thing I will say in defense of the squirts is that they really lube the piston pins well.

The brass bushings in the the top of the rods is subject to wear more than most, and more oil wont hurt a bit.

One big fault of the 6.5 is that it is a top oiler and from my background in racing and performance, this is not a great design.

Oil the crank first off the main gallery and then feed a restricted amount to the cam and top end


The Old Ford FE series "Side oilers" were a great design and case in point.

The standard FE (352,360, 390,428 and some odd ones) were all top oilers but the 427 HP engine blocks were cast with the main oil line along the pan rail and fed the mains first, then the rods fed off the mains and the upper end got the feed up from the bottom.

Feeding the crank from whats left over from the cam and lifters has never been a great plan for an engine that needs good oiling.

Just my 2 cents

[JeepSJ]

Thanks Robyn! If I were to go the route of the aluminum rod, I think I'd drill them through, but at a smaller diameter than the stock squirters, just to retain the lube to the pins.

[Robyn]

The squirts in the 6.5 are drilled holes in the main web saddle that direct oil spray to the piston crown to cool it.

Had they done it with drilled rods it may have been better.

The large drilled holes in the main saddle resulted in serious stress risers and resulted in cracks forming.

Never assemble a 6.5 without breaking every sharp edge and chamfer every hole slightly.

The bottom end of these blocks is loaded with sharp edges, non chamfered holes and such.

Not the total reason for the failures, but eliminating all these can help a lot.